Computers are often connected to various peripheral devices such as scanners, hard disk drives, CD ROM players, tape drives, etc. Communication between the computer and these devices generally follows one of the SCSI standards, which have become the predominant protocols for communication with peripherals for computer systems of all sizes.
A significant drawback of communications using the first two SCSI standards, SCSI-1 and SCSI-2, is that communication is limited to relatively short distances. SCSI devices usually use 50 or 68 pin cables which generally must be less than 25 meters in length. Thus, placing an SCSI device on a network or use of such a device by more than one computer in a network has been difficult. In order to overcome the distance limitation, a third set of standards, SCSI-3, has been developed, which includes three serial network SCSI standards. The three standards include serial storage architecture (SSA), which is generally a local area network (LAN) based standard and has a low bandwidth. Fiber Channel is another SCSI network standard, has a high bandwidth, and is designed for campus-based communications of about 2 kilometers. The third standard is the Generalized Packet Protocol (GPP), which is designed for use over wide-area networks. GPP allows the packetization of SCSI commands and data to permit communication over long distances, such as or found in wide area networks, like the Internet.
In order to use the GPP protocol, it is desirable to develop interfaces with present computer systems and software in order to efficiently access SCSI devices over networks. Preferably, remote SCSI devices should be accessed by an application at a local computer in a manner similar to accessing local SCSI devices. For instance, it is desirable for applications, which take advantage of mirroring of databases on SCSI devices, to utilize remote devices. Mirroring is used to make two or more copies of data on separate storage devices, so that if one device fails, the data will be present on a second device. However, if both devices are at the same location, the system is vulnerable to catastrophic failures such as power outages, floods, or fires in which both storage devices could be harmed or destroyed. Similarly, if the computer attached to those devices fails, access to the information on the storage devices can be temporarily or permanently impaired. It is therefore desirable to utilize remote storage devices, but in a system in which the remote access is transparent to the applications utilizing files on SCSI devices.